Automatic reclosing circuit breaker



A. J. A. PETERSON 1,731,936

AUTOMATIC RECLOSING CIRCUIT BREAKER Oct. 15, 1 929.

2 Sheets-Sheet 1 Fi led April 16. 192:5v

All 2 F/ig,

INVENTOR A/frea J 4. Pefersan WITNESSES: 15M BY W I mE Y' Oct-15, 1929. A. J. A. PETERSON AUTOMATIC RECLOSING CIRCUIT BREAKER 2 Sheets. Sheet 2 Filed April 16, 1923 v I b I INVENTOR A/frea a. A. De Tense/7.

WITNESSES:

ATi'oRNEY Patented Get. 15, 1929 UNETE STATES PATENT OFFICE ALFRED J. A. PETERSON, OF WILKINSBJRG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC 6r, MAN'UFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA AUTOMATIC RECLOSING CIRCUIT BREAKER Application filed April 16, 1923.

My invention relates to automatic sys tems for reclosing circui interrupters and particularly to selective reclosing systems.

One objectof my invention is to provide a reclosing system that may be employed with a plurality of feeder circuits to effect the automatic and selective control of any one of the feeder circuits upon the occurrence of predetermined abnormal conditions therein.

Another object of my invention is to provide a system, of the above-indicated character, wherein a single reclosing unit may operate to reclose one feeder circuit at a time in order to preclude an abnormally heavy drain upon a control source of energy, an an excessive shock on the power system.

A further object of my invention is to pro vide a system, of the above-indicated char actor, in which a single controlling unit may serve to control a plurality of feeder circuits in a predetermined sequence.

Another object of my invention is to provice a control unit, in a system of the aboveindicated character, that shall be operative, upon the occurrence of abnormal conditions in one or more of the circuits to be controlled, to operate the control devices associated with each circuit through a predetermined cycle or schedule before moving to control another feedersubsequently disposed in the predetermined sequence.

Another object of my invention is to provide means whereby a crossed connection between two circuit conductors may be detected and the unit-controlling means rendered inoperative to close the interrupter associated. with one of the circuit conductors so long;- as the crossed connection exists.

In practicing; my invention, I provide for each circuit of the several IEGGC a control relay for the closing coil and a lock-out relay for precluding the energization of the coil when a predetermined abnormal condition persists for a predetern'iined interval of time. I also provide for the control of the several feeders a single control unit com )l'iSinO' a I l l I) selector rela switch a tnnin rela and also .7 a 2-3 .7 what is termed a set-up or control relay for the selector. This apparatus is similar Serial No. 632,274.

to that shown and described in copending app ication Serial No. 608,300, filed Decemher 21, 1922, by Charles McL. Moss, lVilliam Farley and Alfred J. A. Peterson, and assigned to the assignee of the present application.

lVhen a circuit interrupter is opened by reason of abnormal conditions in the circuit, the selector act-uates a drum controller mechanism to subject the closing coil of the interrupter to the controlling influence of the timing and the set-up relays. The interrupter is thereupon reclosed.

If the faulty condition persist and the interrupter opens immediately, the timing and the set-up relay co-operate to effect a second reclosure of the interrupter after a predetermined interval, and, if the interrupter opens again, a third reclosure thereof is effected after another interval. If, after the third reclosure, the interrupter again opens, indicating a persisting faulty condition, the lockout relay associated with the interrupter is caused to operate to preclude further energiaation of the closing coil.

If the interrupter should remain closed after any one of the three reclosures, the timing and the set-up! relays will be disconnected from the closing mechanism of the interrupter. If, in the meantime, the interrupter of another feeder circuit has been opened by reason of faulty conditions therein, the selectorwill move the control of the timing and the set-up relays to a switch associated with tl second faulty circuit. The same cycle or schedule of operations is cffected until the interrupter of that circuit is either rcclosed or locked out.

If the conductors of two different feeder circuits should become crossed, one of the circuits would be immediately disconnected and possibly both by the overload relay de vices assoc'ated therewith. If both circuits should be disconnected, the reclosing unit would immediately operate to close the interrupter associated with one circuit to reconnect the same to the system. Since the second circuit, with which the now reclosed circuit crossed, is not energi ed from the main system, a normal. conditi u will he indiceted in the first circuit and the control unit would move on to the second feeder circuit.

Upon reclosing the second circuit, the crossed connection would be re-established and both circuits would again be re-opened. Since the control unit is still in position to control the second feeder circuit, its inter- ;upter will be reclosed. The second circuit would then remain closed since a normal condition would be indicated in that circuit.

The control unit will, however, again be actuated to move on to efiect the reclosure of th first circuit and this procedure will be continued until the crossed connection is clear.

In order to obviate such condition of continual operation, I provide means whereby the reclosing of an interrupter is precluded if the feeder circuit is energized from any source or through any interrupter other than its own source of energy or through its associated circuit interrupter.

Figure 1 of the accompanying drawings is a diagrammatic view of an electrical system illustrating the arrangement of the control apparatus for two feeder circuits connected to operate in accordance with my invention, and

Fig. 2 is a schematic diagrammatic view illustrating, in simplified form, the several circuit connections of the system that is illustrated in Fig. 1.

Referring to the accompanying drawings, energy is supplied from a supply circuit 1 to a plurality of feeder circuits 2 and 3 through circuit interrupters t and 5, respectively. The interrupter d is provided with a closing coil and a trip coil 11. The circuit of the trip coil 11 is controlled by an overload relay 12 which is energized, in accordance with the current traversing the feeder circuit, through a current transformer 13. The interrupter l 'is also pr vided with an auxiliary interlock switch 15 that is open when the main contacts of the circuit interrupter are open, and two switches 16 and 1'? tnat are closed when the main contacts of the interrupter are open.

The circuit oi the closing coil 10 of the interrupter is controll d by an auxiliary relay switcn. 18, the operating circuit of which is controlled by relay l9, vhich I shall hereaiterterm the cutofi? relay.

The functionoi' the cut-oil relay 19 is to open the circuit or" the closing coil 10 by deenergizing the relay switch 18 after each closure of the interrupter l.

The relay 19 comprises two switches 20 and 1 that are normally closed and two switches 2 and that are normally open when the "clay is ale-energized. The relay further comorises an operating coil 23, that serves to actuate the switches 20, 21, 22 and 25 from their de-energized positions, and a holding coil 24 that serves to maintain the. switches in their energized positions so long as the hold Ti ing coil is energized, irrespective of whether the operating coil 23 remains energized or not. The construction of this relay is such that the holding coil 24- does not have sufiicient torque to operate the relay, but merely sur'licient to maintain the relay in its energized position after it has been actuated thereto by the operating coil 23.

The interrupter 4 of the feeder circuit 2 is also provided with another relay 26, which I shall hereafter term the lock-out relay. The function of the lock-out relay 26 is to preclude further automatic control of the interrupter after a fault occurs and persists beyond the time required to actuate the interrupter through a predetermined cycle of o erations. The lock-out relay 26 comprises two switches 27 and 28 that are open in the de-energized po sition of the relay, an operating coil 29 that serves to actuate the switcnes to their respective closed positions, and a holding coil 30 that serves to maintain them in closed position, irrespective oi' the energization of the coil 29. The construction and the operation of the look-out relay is simila" to that e-;")lainec above in connection with the cut-off relay 19.

The control apparatus associated with the interrupter l comprises further a voltage relay 32 that is energized from a potential transformer 33, the primary winding-of which is connected to the feeder circuit 2. The relay 32 is adjusted to require a predetermined time into "val in its operation. The relay is provided, in addition to its main contact members, with a back interlock 34.

A resistor 35 is connected in parallel with the operating coil of relay switch 18 to provide an additional current-carrying path for the operating coil of another control relay, as will be hereinafter explained. V

The feeder circuit 3 and the interrupter 5 associated therewith are provided with control equipment similar to that enumerater above as associated with the circuit 2 and the interrupter 4E. The apparatus that is associated with the interrupter 5 will be re ferred to by numerals similar to those applied to apparatus of feeder circuit 2 except in the 100 series. F or examplathe closing coil 10 or" the interrupter 4 will correspond to the closing coil 110 of the interrupter 5. 7

Any number of feeder circuits, equipped with control apparatus similar to that here inabove described, may be controlled, in any predetermined sequence, by the following apparatus, that is arranged to consti ute a single control unit. Such apparatus con1- prises, in general, a motor-driven sequence switch or selector 51, a set-up relay 52 and a timing relay 53.

The selector 51 comprises a unidirectional motor 54: and a drum controller compris ing a plurality of segments 55 that are adapted, in different positions of the controller, to severallyengage a plurality of stationary contact members 56, 57 and 58. To control more feeder circuits, only an additional contact member need be employed on the drum for each additional circuit.

The set-up relay 52 is similar in construction and in operation to the cut-off and the lock-cut relays 19 and 26 previously de scribed, and it comprises two switches 60 and 61 that are normally open, two switches 62 and 63 that are normally closed, an operating coil 64 for actuating the switches and a holding coil 65 for maintaining them in the position to which they are actuated.

The timing relay 53 comprises a motor 68 and a movable bridging member 69 that is controlled thereby through gearing of proper ratio to engage and bridge the three sets of contact members 70, 71 and 72, respectively. The timing relay 53 may be adjusted to cause the bridging member 69 to control the three sets of contact members in a predetermined sequence after predetermined intervals, for example, the relay may be adjusted to effect the bridging of the contact members 70 thirty seconds after the relay is energized, the bridging of the contact members 71 one minute later and the bridging of the contact members 72 two minutes later. These time intervals are specified merely by Way of example and they may be respectively adjustd to suit the conditions of any particular system, as desired.

The timing relay 53 is of the clutch type and the switch element 69 is immediately reset at its initial position when the relay is de-energized. The timing of the relay is not, therefore, cumulative as between two successive circuits that are controlled thereb Let it be assumed that the interrupters of the respective feeder circuit interrupters have been closed to energize the associated circuits. Upon the occurrence of abnormal conditions in the circuit 2, the interrupter 4 opens. The following operation thereupon occurs.

As will be seen by referring to circuit A of Fig. 2, the circuit of the motor 54 of the selector relay 51 will be energized by the closing of the auxiliary interlock switch 17 of theinterrupter 4 to complete a circuit from the positive conductor 75 of a source of control energy through the switch 21 of the cut-off relay 19, the motor 54 and the switch 63 of the set-up relay 52, to the negative bus 76 of the control source. The motor 54 will thereupon actuate the drum until the segments 55 engage the contact members 56 and 57.

The operating coil 64 of the set-up relay 52 will thereupon be energized. The circuit thereof may be traced, upon reference to circuits D and G, from the negative control bus 76 through the operating coil 64 of the set-up relay, contact members 56 and 57 and bridging segments 55, conductor 78, interlock switch 34 of relay 32, switch 20 of the cut-off relay 19, and the operating coil of the relay switch 18 and the resistor 35 in parallel, to the positive conductor 75. The resistor 35 serves to provide an additional current-carrying path that will permit sufiieient current to energize the operating coil 64 to operate the set-up relay 52. The relay switch 18, however, is not energized to a sufficient degree to cause it to close.

Immediately upon the energization, however, of the operating coil 64, the holding coil 65, which is always energized in series with the resistor 66 between the positive and negative conductors 75 and 7 6, illustrated in circuit C, serves to maintain the set-up relay 52 in its energized position. The switches 60 and 61 are thereupon closed and the switches 62 and 63 opened. The switch 60 short-circuits he operating coil 64, as will be seen by reference to the circuit D of Fig. 2, and there upon reduces the resistance of the circuit Gr including the relay switch 18, sufficiently to permit that switch to close. The closing coil 19 of the interrupter is thereupon energized to close the interrupter.

As soon as the interrupter 4 closes, interlock switch 15 closes circuit F to connect the operating coil 23 of the cut-off relay 19 beveen the positive and negative conductors 75 and 76. The cut-off relay 19 is thereupon actuated to close switch 22 and to open switches 26 and 21. Switch 20, in opening, opens the circuit of the coil of relay switch 18, whereupon the closing coil 10 is de-ener gized. This operation is illustrated in circuit G of Fig. 2. The cut-off relay 19 is then maintained in its energized position by the hold ing coil 24, circuit H, the circuit of which is completed from the positive conductor 7 5 to the negative conductor 76 through a resistor 73, control bus conductor 77, holding coil 24 of relay 19, conductor 78, contact members 56 and 57 and segments 55 of the selector, and switch 60 of tire set-up relay 52.

If the fault which caused the interrupter to open is cleared, the interrupter 4 will remain closed. If the faulty condition persists, however, the interrupter 4 will immediately be opened by the operation of the overload relay 12 after a time interval depending upon its time setting.

Let it be assumed first that the faulty condition is cleared and that the interrupter 4 remains closed. Under such conditions, the relay 32 will be energized to close its switch after the predeterminedinterval for which. it has been set to operate, for example, two seconds. The switch 32, in closing, short-circuits the holding coil 65 of the set-up relay 52 through conductors 79 and 80, relay switch 32, conductors 78, contact members 56 and 57,

segments 55 of the selector, switch 60 and the holding coil- 65 of the set-up relay 52 through conductor 81. The set-up relay 52 is thereupon permitted to return to its initial posi tion to open the switch 60 and remove control potential from the segments 55 of the selector 51. The interrupter remains closed and the control apparatus is de-energized. 7

Let it now be assumed that the faulty condition of the circuit 2 is a persistent one and that the interrupter is immediately reopened after its first reclosure. The relay 32' has not had sullicient time to close its switch since, normally, its time setting is greater than the time setting of the overload relay 12. The set-up relay 52 is therefore still in its energized position. Switch 61 of Set-up relay 52 connected t is operating motor 68 of the timing relay 53 between the control conductors 7 5 and 76 immediately upon the actuation of the set-up relay 52, as is illustrated in circuit B. Since the interrupter l was reopened within two seconds after its first reclosure, by reason of the persisting faulty condition, and the set-up relay 52 is still in its energized position, the timing relay 53 will continue to 0perate until the contact members 70 are bridged by the bridging member 69.

The bridging of the contact members 70 completes a short-circuit around the holding coil 24 of the cut-ofi relay 19 which has remained energized. The cut-off relay 19 is thereupon permitted to return to its initial position. As illustrated by circuits D and H,

V theshort-circuit around the holding coil 24 may be traced from one terminal of the coil through conductor 78, the contact members 56 and 57 and the segments 55 of the selector, the contact members 7 O of the timing relay 53, and conductors 82 and 77 to the other terminal of the coil 24.

l l hen the cut-oil relay 19 returns to its initial position, the switch 20 is closed and the circuit of the operating coil of the auxiliary relay switch 19 is re-energized, as previously described and illustrated in circuit G, whereupon the closing coil 10 is energized to reclose the interrupter 4 a second time.

It the feeder circuit 2 should now be clear of abnormal conditions,.the set-up relay 52 will be tic-energized, as previously described, and the control unit will be available for the control of another feeder circuit. If, however, the faulty condition of circuit 2 still persists, the interrupter 4 will again be opened, and, after a predetermined interval determined by the setting between the contact ncmbers 7 0 and 71, the latter set of contact members will be bridged to efiect the third reclosure of the interrupter 4.

As previously explained, the control unit will be disconnected if the feeder circuit is now clear of faulty or abnormal conditions. If the abnormal conditions still persist after such third reclosure, the timing relay 53 will continue to operate until the contact mem bers 72 are bridged. The operating coil 29 of the look-out relay 26 will thereupon be energized, as illustrated in circuits E and K, from the positive control conductor 75 through the set of contact members 72, of the timing relay 53, a common condutor 83, the operating coil 29 of the look-out relay 26,

switch of cut-off relay 19, conductor 78,

contact members 56 and 57 and segment 55 of the selector 51 and switch 60 of the set-up relay 52 to the negative conductor 76.

The lock-out relay 26 is thereupon actuated to its energized position whereupon a circuit is completed by the switch 27 through the holding coil that maintains the latter energized tohold the lock-out relay in its energized position.

Simultaneously, switch 28 of the lock-out relay closes and co-operates with the switch 22 f the cut-off relay 19 which is still in its energized position to short-circuit the holding coil 65 of the set-up relay 52. This circuit, as illustrated by circuits 0 and J in Fig. 2, may be traced from one terminal of the holding coil 65 through conductor 81, conductor 79, switch 28 of lock-out relay 26, switch 22 of cut-0E relay 19, conductor 78, contact members 56 and 57 and segments of the selector, switch 60 of the set-up relay 52 to the other terminal of the holding coil of the latter relay. The set-up relay 52 is thereupon permitted to return to its initial position. In such position, the switch 63 is closed to permit the energization of the selector motor 54 when any other circuit interrupter is opened by reason of abnormal conditions in the associated circuit, as illustrated in circuit A.

Similarly, the closure of switch 62 of the set-up relay 52 short-circuits the motor 68 and the clutch of the timing relay 53 whereupon the bridging member 69 is permitted to return to its initial position. The respective elements 51, 52 and 53 that constitute the common control equipment are now available to control the next interrupter Which may be opened.

When the abnormal or faulty condition ocours in only the circuit being controlled, the interrupter may be controlled through a predetermined cycle of operations and then permitted to remain closed or locked out, depending upon the condition of the circuit. lVhen the abnormal condition, however, is caused by the crossed connection of the conductors of two difierent circuits, it is necessary to preclude the simultaneous connection of both circuits to the main system or source of energy, since simultaneous connection of both circuits to the system will constitute a short-circuit thereon unless it happens that the crossed conductors be connected to the same phase or to the terminals of like polarity of the source of energy.

It conductor A of circuit 2 and conductor B of circuit 3 should become cross connected in some manner, the circuit including these conductors would be traversed by an excessive current that would energize the associated overload relays.

Let it be assumed that the circuit 2 has been traversed by a current heavier than that traversing the circuit 3 and that the interrupter f has been opened to disconnect the circuit from the main source of energy 1. The control unit would thereupon be set in operation, as previously described, by the cooperation of the interlock switch 17 of the in terrupter at and the switch 21 of the cut-off relay 19. However, since the relay switch 32 that is energized from the transformer associated with the conductor A of circuit 2 would be energized by the potential impressed upon the conductor A by reason of its connection to the conductor B of circuit 3, that relay would be in its energized position at which its back interlock 34 would be opened.

The operating circuit of the relay 18 would therefore be opened between the contact member 57 of the selector control relay 51 and the operating coil of the relay 18 to preclude the energization thereof so long as the crossed connection continued between the conductor A of the circuit 2 and the conductor B of the circuit 3.

Under such conditions, the reconnection of the feeder circuit 2 to the main source of en ergy 1 would be precluded but the selector motor relay 51 would be maintained energized and it would continue to rotate so long as the crossed connection continued.

By disposing a switch 90 in a signalling circuit 91 to effect its operation each time the selector motor relay 51 makes one complete revolution, an attendant at the station or a supervisor at a distance may be notified by a signalling device 92 at the station, or by a signal over the circuit of a dispatching system, when an abnormal condition exists which is causing the continuous operation of the selector motor relay. A continuously periodic energization of the signalling device or of the signalling circuit will therefore indicate to the attendant or to the system supervisor the existence of such a condition and an inspector may thereupon be detailed to locate and clear the trouble.

By means of such an arrangement of interlocking circuits, the continual alternate reclosing of the interrupters associated with two cross-connected circuits and the incidental depreciation of the apparatus and surges on the system may be obviated.

It may happen, under some conditions, that the load upon a feeder circuit is slightly in excess of the normal operating load and that the overload relays associated with the circuit will therefore operate, but only after a relatively long interval of time. By interlocking the energizing circuit of the timing relay switch 32 through the back interlock switch of the associated overload relay 12, the premature disconnection of the control unit may be obviated, to permit the interrupter to be controlled through the predetermined cycle of operations before the control unit moves forward to control another circuit.

In the system which I have illustrated, the circuit interrupters comprise single-pole elements which may be individually controlled. For the sake of simplicity, I have shown merely one of the single-pole breakers associated with different conductors of the two feeder circuits that are illustrated. The several single-pole elements may be arranged to be closed in sequence in a manner similar to the arrangement for the several feeder circuits. For this purpose additional contact members 57 and 57" are provided on the drum of the selector relay for the single-pole elements of the interrupter associated with the feeder circuit 2. Similarly, contact members 58 and 58" are provided for the other single pole elements of the interrupter 5 associated with the feeder circuit 3.

My invention therefore comprehends both the prevention of the premature disconnection of the control unit from the circuit which it is controlling, and also the arrangement of means for detecting a condition of crossed connections between separate circuit conductors and the subsequent control of the controlling unit to preclude the simultaneous connection of both crossed circuits to the main source of energy.

My invention is not limited to the specific apparatus illustrated nor to the particular arrangement thereof, since it may be variously modified without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. In a power distribution system, the combination with a plurality of feeder circuits, means for opening the respective circuits upon the occurrence of abnormal conditions therein and automatic means for subsequently reclosing the faulty feeder circuits, of means associated with each circuit for detecting a crossed connection between that circuit and another circuit when energized, and means controlled thereby to preclude the automatic reclosure of the firstanentioned circuit while said crossed connection obtains.

2. In a power distribution system, the combination with a plurality of feeder circuits, means for opening the respective circuits upon the occurrence of abnormal conditions therein and automatic means for subsequently reclosing the faulty feeder circuits, of a selector for controlling the automatic reclosure of the feeder circuits after an automatic opening thereof, means for effecting the op eration of the selector upon the opening of a circuit, means associated with each circuit for rendering the selector ineffective to re close said circuit after the opening thereof by reason of a crossed connection with another feeder circuit, and means for indicating a continuous ineffective operation of the selector.

3. In a power system, the combination with a plurality of circuit conductors, a common source of energy therefor and connecting means between said source of energy and the respective conductors, of a selector for controlling the connecting means, means operative when the connecting means are opened to effect the operation of the selector to control the reclosing of said connecting means, and means operative upon a crossed connection between two circuit conductors for rendering the selector ineffective to reclose the connecting means associated with one of the conductors.

4. In a power distributing system, the combination with a supply circuit, a plurality of feeder circuits energized therefrom a circuitcontrolling device provided with closing and tripping mechanism for connecting each feeder circuit to the supply circuitand a common source of control e ergy for tne closing mechanisms, of means responsive to a predetermined abnormal condition in a feeder circuit for actuating the tripping mechanism of the associated controlling device, means for effecting the automatic closure of the several controlling devices singly in a predetermined sequence to obviate a heavy drain on the source of control energy and an excessive shock on the power system and means operative upon the occurrence of a crossed connection between two feeder circuits for rendering the closure-controlling means inefiect-ive in one of said controlling devices.

5. In a power distributing system, the combination with a supply circuit, a plurality of feeder circuits energized therefrom, a circuit-controlling device provided with closing and tripping mechanism for connecting each feeder circuit to the supply circuit and a common source of control energy forthe closing mechanisms, of means responsive to a predetermined abnormal condition in a feeder circuit for actuating the tripping mechanism of the associated controlling devices, means for controlling the closing mechanism of the associated devices and unit means for controlling said controlling means singly in a predet rmined sequence, and means for rendering the unit means ineffective to operate the controlling means associated with the closing mechanism of one of two circuit-controlling devices associated with. two feeder circuit conductors which have became cross connected.

6. In a power distributing system, the com bination with a supply circuit, a plurality of feeder circuits energized therefrom, a circuit-controlling device provided with closing and tripping mechanism for connecting each feeder circuit to the supply circuit and a common source of control energy for the closing mechanisms, of means responsive to a predetermined abnormal condition in a feeder circuit for actuating the tripping mechanism of the associated controlling device, means for controlling the closing mechanism of the associated devices and unit means for controlling said controlling means singly in a predetermined sequence, means controlled by each of the feeder circuit controlling devices for initiating the operation of said unit means, and means associated with one of two circuit conductors that have become cross connected for rendering the unit means ineffective to effect the operation of the circuit-controlling devices associated with one of the circuit conductors.

7. In a power distributing system, the combination with a supply circuit, a plurality of feeder circuits energized therefrom, a circuitcontrolling device provided with closing and tripping mechanism for connecting each feeder circuit to the supply circuit and a common source of control energy for the closing mechanisms, of means responsive to a predetermined abnormal condition in the feeder circuit for actuating the tripping mechanism of the associated controlling device, means for controlling the closing mechanism of an associated device, unit means for controlling said closing mechanism-c0ntrolling means through a predetermined cycle of operation, and a selector for selectively subjecting the mechanism-controlling means to the unit controlling means, and'means operative in response to a condition indicative of crossed connections between two feeder circuit conductors for rendering the sequencecontrolling means ineffective to control the closing mechanism associated with one of the crossed circuit conductors. V

8. In a power distributing system, the com bination with a supply circuit, a plurality of feeder circuits energized therefrom, a circuit-controlling device provided with closing and tripping mechanism for connecting each feeder circuit to the supply circuit and a common source of control energy for the closing mechanisms, of means responsive to a predetermined abnormal condition in a feeder circuit for actuating the tripping mechanism of the associated controlling device,means for controlling the closing mechanism of an associated device, unit means for controlling said closing mechanism-controlling means through a predetermined cycle of operation, a selector for selectively subjecting the mechanism-controlling means to the unit controlling means, and means for rendering said selector ineffective to subject one of the mechanism-controlling means to the unit controlling means, comprising means operative in response to a condition of ALFRED J. A. PETERSON. 

